Boat trailer lights are typically submerged in water during launch and retrieval of boats. If water enters the lamp assembly it may cause the bulbs to shatter due to the temperature difference between the glass and the water or it may cause corrosion in the contacts of the fixture on the bulb or both, thus, resulting in a subsequent failure.
In order to overcome this problem, various methods have been tried. Some have utilized the air entrapment principle, where one end of the housing for the bulb is sealed and the other is open allowing water to enter. During launch the rising water compresses the air and prevents the water from contacting the bulb. These methods often fail as the water will slosh about during motion of the trailer on rough ramp surfaces. U.S. Pat. Nos. 3,106,349, 3,858,038, 4,617,617 and 5,136,484.
Others have described a bulb compartment which is permanently sealed to prevent water access, but such do not allow bulb replacement. U.S. Pat. Nos. 5,060,121 and 5,150,954.
Another method which allows bulb replacement and yet allows for a water-tight enclosure is to use flexible gaskets to ensure a tight seal. These methods have encountered problems when bulbs are replaced by the user due to the necessity of ensuring that the seal not be broken around the mounting means. The current invention is an improvement in the above method as it provides for a mounting means apart from the gasket, thus ensuring a water-tight bulb compartment upon replacement of the bulbs.
With the existing gasket sealed enclosures the fastening means require a watertight seal. The present invention is such that the internal enclosure which completes the watertight compartment about the bulb fixture has one continuous surface at its bottom edge. The fastening means do not require separate gasket to maintain the watertight compartment about the bulb fixture.